The production of organic products from bodies of oil shale comprising layers of kerogen embedded in a mineral formation has heretofore been accomplished by mining and suitably pulverising the formation of oil shale. The shale is then retorted above ground and products derived from kerogen are driven off from the shale. In order to achieve sufficiently rapid decomposition of kerogen to obtain efficient and economical utilization of equipment, temperatures around or above 500.degree. C. (or higher) have generally been used, and at such temperatures the kerogen in the shale is partially converted into liquid organic products having high pour points, which require hydrogenation to convert the products to low pour point liquids suitable for flowing through pipe lines at normal temperatures.
In addition, the capital cost of such mining equipment and the retorting energy cost tend to render shale mining and above ground retorting processes economically unattractive.
Also, the spent shale from the above ground retorting process has a volume substantially greater than the volume of the original shale, and creates a major disposal problem. Also, water soluble products in the spent shale can be a source of pollution to surrounding areas.
Attempts to covert kerogen to liquid and gaseous products in situ in the oil shale by injecting heated fluids, such as steam, methane or hot combustion gases, through injection wells, or by putting a D.C. voltage between spaced wells, have generally been unsatisfactory and produced little or no yield of shale oil. As important reason for this is the fact that oil shale is generally found as an impervious monolithic stratum without suitable fractures or passages for accepting the flow of heated fluids intended to heat the structure. In addition, if the heating depends entirely on thermal conduction through the shale, the shale will require periods of time on the order of years for the temperature to be uniformly distributed through a large body of oil shale by thermal conduction, if fractured by conventional oil field methods using hydrostatic pressure, which have generally proved to be inadequate for producing conduits for fluid heating media.